Founded in 1928, Maersk Line is now the world’s largest container-shipping company—no small feat in such a cutthroat industry. There are approximately 400 liner services in direct competition with one another. To survive, Maersk Line must attract new business constantly and retain its 59,000 customers worldwide.

In 2013, when Maersk Line received a weak Net Promoter Score that indicated the company had 10 percent more detractors than promoters, its customer service excellence (CSE) te